Implement syntax for transition tables in AFTER triggers.

This is infrastructure for the complete SQL standard feature.  No
support is included at this point for execution nodes or PLs.  The
intent is to add that soon.

As this patch leaves things, standard syntax can create tuplestores
to contain old and/or new versions of rows affected by a statement.
References to these tuplestores are in the TriggerData structure.
C triggers can access the tuplestores directly, so they are usable,
but they cannot yet be referenced within a SQL statement.

7 files changed, 43 insertions, 2 deletions

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index cd3048db868..880559650ad 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201610201
+#define CATALOG_VERSION_NO	201611041
 
 #endif
diff --git a/src/include/catalog/pg_trigger.h b/src/include/catalog/pg_trigger.h
index eb39c50e637..da6a7f3a2e6 100644
--- a/src/include/catalog/pg_trigger.h
+++ b/src/include/catalog/pg_trigger.h
@@ -59,6 +59,8 @@ CATALOG(pg_trigger,2620)
 #ifdef CATALOG_VARLEN
 	bytea tgargs BKI_FORCE_NOT_NULL;	/* first\000second\000tgnargs\000 */
 	pg_node_tree tgqual;		/* WHEN expression, or NULL if none */
+	NameData	tgoldtable;		/* old transition table, or NULL if none */
+	NameData	tgnewtable;		/* new transition table, or NULL if none */
 #endif
 } FormData_pg_trigger;
 
@@ -73,7 +75,7 @@ typedef FormData_pg_trigger *Form_pg_trigger;
  *		compiler constants for pg_trigger
  * ----------------
  */
-#define Natts_pg_trigger				15
+#define Natts_pg_trigger				17
 #define Anum_pg_trigger_tgrelid			1
 #define Anum_pg_trigger_tgname			2
 #define Anum_pg_trigger_tgfoid			3
@@ -89,6 +91,8 @@ typedef FormData_pg_trigger *Form_pg_trigger;
 #define Anum_pg_trigger_tgattr			13
 #define Anum_pg_trigger_tgargs			14
 #define Anum_pg_trigger_tgqual			15
+#define Anum_pg_trigger_tgoldtable		16
+#define Anum_pg_trigger_tgnewtable		17
 
 /* Bits within tgtype */
 #define TRIGGER_TYPE_ROW				(1 << 0)
@@ -142,4 +146,11 @@ typedef FormData_pg_trigger *Form_pg_trigger;
 #define TRIGGER_TYPE_MATCHES(type, level, timing, event) \
 	(((type) & (TRIGGER_TYPE_LEVEL_MASK | TRIGGER_TYPE_TIMING_MASK | (event))) == ((level) | (timing) | (event)))
 
+/*
+ * Macro to determine whether tgnewtable or tgoldtable has been specified for
+ * a trigger.
+ */
+#define TRIGGER_USES_TRANSITION_TABLE(namepointer) \
+	((namepointer) != (char *) NULL)
+
 #endif   /* PG_TRIGGER_H */
diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 0ed7c86eb27..c6e3e2c2346 100644
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -37,6 +37,8 @@ typedef struct TriggerData
 	Trigger    *tg_trigger;
 	Buffer		tg_trigtuplebuf;
 	Buffer		tg_newtuplebuf;
+	Tuplestorestate *tg_oldtable;
+	Tuplestorestate *tg_newtable;
 } TriggerData;
 
 /*
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 88297bbe803..cb9307cd000 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -453,6 +453,7 @@ typedef enum NodeTag
 	T_OnConflictClause,
 	T_CommonTableExpr,
 	T_RoleSpec,
+	T_TriggerTransition,
 
 	/*
 	 * TAGS FOR REPLICATION GRAMMAR PARSE NODES (replnodes.h)
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 6de2cab6b26..9b600a5f76d 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1204,6 +1204,21 @@ typedef struct CommonTableExpr
 	 ((Query *) (cte)->ctequery)->targetList : \
 	 ((Query *) (cte)->ctequery)->returningList)
 
+/*
+ * TriggerTransition -
+ *	   representation of transition row or table naming clause
+ *
+ * Only transition tables are initially supported in the syntax, and only for
+ * AFTER triggers, but other permutations are accepted by the parser so we can
+ * give a meaningful message from C code.
+ */
+typedef struct TriggerTransition
+{
+	NodeTag		type;
+	char	   *name;
+	bool		isNew;
+	bool		isTable;
+} TriggerTransition;
 
 /*****************************************************************************
  *		Optimizable Statements
@@ -2105,6 +2120,8 @@ typedef struct CreateTrigStmt
 	List	   *columns;		/* column names, or NIL for all columns */
 	Node	   *whenClause;		/* qual expression, or NULL if none */
 	bool		isconstraint;	/* This is a constraint trigger */
+	/* explicitly named transition data */
+	List	   *transitionRels; /* TriggerTransition nodes, or NIL if none */
 	/* The remaining fields are only used for constraint triggers */
 	bool		deferrable;		/* [NOT] DEFERRABLE */
 	bool		initdeferred;	/* INITIALLY {DEFERRED|IMMEDIATE} */
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 17ffef53a70..77d873beca7 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -251,6 +251,7 @@ PG_KEYWORD("names", NAMES, UNRESERVED_KEYWORD)
 PG_KEYWORD("national", NATIONAL, COL_NAME_KEYWORD)
 PG_KEYWORD("natural", NATURAL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("nchar", NCHAR, COL_NAME_KEYWORD)
+PG_KEYWORD("new", NEW, UNRESERVED_KEYWORD)
 PG_KEYWORD("next", NEXT, UNRESERVED_KEYWORD)
 PG_KEYWORD("no", NO, UNRESERVED_KEYWORD)
 PG_KEYWORD("none", NONE, COL_NAME_KEYWORD)
@@ -268,6 +269,7 @@ PG_KEYWORD("of", OF, UNRESERVED_KEYWORD)
 PG_KEYWORD("off", OFF, UNRESERVED_KEYWORD)
 PG_KEYWORD("offset", OFFSET, RESERVED_KEYWORD)
 PG_KEYWORD("oids", OIDS, UNRESERVED_KEYWORD)
+PG_KEYWORD("old", OLD, UNRESERVED_KEYWORD)
 PG_KEYWORD("on", ON, RESERVED_KEYWORD)
 PG_KEYWORD("only", ONLY, RESERVED_KEYWORD)
 PG_KEYWORD("operator", OPERATOR, UNRESERVED_KEYWORD)
@@ -313,6 +315,7 @@ PG_KEYWORD("recheck", RECHECK, UNRESERVED_KEYWORD)
 PG_KEYWORD("recursive", RECURSIVE, UNRESERVED_KEYWORD)
 PG_KEYWORD("ref", REF, UNRESERVED_KEYWORD)
 PG_KEYWORD("references", REFERENCES, RESERVED_KEYWORD)
+PG_KEYWORD("referencing", REFERENCING, UNRESERVED_KEYWORD)
 PG_KEYWORD("refresh", REFRESH, UNRESERVED_KEYWORD)
 PG_KEYWORD("reindex", REINDEX, UNRESERVED_KEYWORD)
 PG_KEYWORD("relative", RELATIVE_P, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/reltrigger.h b/src/include/utils/reltrigger.h
index e87f2283ec8..756b417128a 100644
--- a/src/include/utils/reltrigger.h
+++ b/src/include/utils/reltrigger.h
@@ -39,6 +39,8 @@ typedef struct Trigger
 	int16	   *tgattr;
 	char	  **tgargs;
 	char	   *tgqual;
+	char	   *tgoldtable;
+	char	   *tgnewtable;
 } Trigger;
 
 typedef struct TriggerDesc
@@ -68,6 +70,11 @@ typedef struct TriggerDesc
 	/* there are no row-level truncate triggers */
 	bool		trig_truncate_before_statement;
 	bool		trig_truncate_after_statement;
+	/* Is there at least one trigger specifying each transition relation? */
+	bool		trig_insert_new_table;
+	bool		trig_update_old_table;
+	bool		trig_update_new_table;
+	bool		trig_delete_old_table;
 } TriggerDesc;
 
 #endif   /* RELTRIGGER_H */